The overall objective of this investigation is to gain insight into the synthesis and function of glycoproteins in embryonic development. 1. In order to study the processes that regulate the turnon in synthesis of N-linked glycoproteins prior to gastrulation of sea urchin embryos, we will isolate mRNA at various stages of development and translate it in an in vitro translation-glycosylation system. This study should tell us if glycosylatable polypeptides are translated throughout development, but only become glycosylated at gastrulation, or if new, glycosylatable proteins are first translated at this time. In addition, we will extend studies on metabolism of dolichol phosphate, the lipid-carrier involved in glycosylation, as a function of development. 2. To understand how N-glycoproteins are involved in gastrulation we will microinject into the blastocoel of early gastrula embryos lectins, glycopeptides, and antibodies to one or more of the glycoproteins that begin to be synthesized at the time of gastrulation. These studies should allow us to determine if the glycoproteins synthesized during gastrulation directly participate in the cell-cell recognition events involved in gut formation. 3. Since the function of the glycoprotein-rich yolk platelets during development of the sea urchin embryo is unknown, we will ultrastructurally and biochemically characterize isolated platelets. We will carry out pulse-chase experiments to see if the yolk platelets are metabolically active and, if so, if they serve as donors of constituents to other subcellular membranes. 4. Synthesis of glycoproteins, as well as processing of a novel hydroxyproline-containing protein (HyPP), are required for embryonic sea urchin cell to differentiate in vitro and form spicules. The localization of these proteins in the cellspicule complex will be studied. The possibility that either synthesis or processing of HyPP is developmentally regulated will be investigated. Also, we will study the events involved in the massive entry of Ca++ into the cells that occurs during spicule production. 5. Using an in vitro culture system for mouse embryos, we will determine if very early embryos actively synthesize dolichol or if it premade the eggs. Possible activation of enzymes involved in mobilization of stored dolichol will be investigated. In addition, we will attempt to determine why compactin, an inhibitor of mevalonic acid biosynthesis, blocks development.